Shared room in Melbourne?

Hello mates,I;m going to move to Melbourne in november with my girlfriend and I;m searching for an accomodation to rent. Precisely, I;m searching for a double room close to the centre. I;ve discovered that realestate.com.au does not show the real price of the properties: sometime they don;t exist, or they have higher prices. Do you know a good solution to rent? where can I find what I;m searching for?